This is my trade, and it was indeed a mistake on my part to close it without confirming whether the XMR had been sent on your side. My understanding was that it had not, but in any case we make it a practice to confirm this with the buyer before closing to avoid exactly this situation. I will re-open the dispute now and attempt to contact the seller to either (a) send your XMR payment back or (b) transfer the BTC to you after all. You should be able to communicate with me about it within the app once the trade is re-opened, but if you cannot, please PM me here on the forum and we can resolve it there.